[Pw_forum] convergence NOT achieved after 100 iterations: stopping (even for a relaxed structure from VASP)

[Ari P Seitsonen]

Dear Masood Yousaf,

   Please try multiplying your lattice vectors laterally by two; I would 
also try the 'mixing_mode = "local-TF"': That works better for me in 
inhomogeneous systems such as slabs (ie where there are high-density 
regions and vacuum).

   Some other notes:

  - Why not using 'ibrav = 4' and 'a', 'c' to define the lattice vectors? 
You would have much better accuracy, symmetries etc. Likewise for the 
coordinates, more precise digits would allow finding symmetries etc

  - Eventually the FHI potentials will need much higher cut-off energy, I 
seem to remember something like 90-120 Ry for Ni... (just for curiosity, 
I had the honour to share the office for some time with the GPP, Guru of 
Pseudo Potentials, at FHI, from whom the parametres of these pseudos might 
still originate from ;)

     Good Luck from Almost-Sunny Montrouge,

        apsi

-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-
   Ari Paavo Seitsonen / Ari.P.Seitsonen at iki.fi / http://www.iki.fi/~apsi/
   Ecole Normale Supérieure (ENS), Département de Chimie, Paris
   Mobile (F) : +33 789 37 24 25    (CH) : +41 79 71 90 935


On Thu, 8 Oct 2015, Masood Yousaf wrote:

> Dear Members,
> 
> Kindly have a look at the input file and suggest  why its so hard to
> converge this relatively moderate system. I tried to fix in different ways
> but failed. I tried the same structure in VASP and had no problem. I want to
> calculate RAMMAN spectra and that can only be calculated with LDA functional
> in Quantum espresso. I am using QE 5.1.
> 
> 
>  &control
>     calculation='relax'
>     restart_mode='from_scratch'
>     pseudo_dir = '/share/QE_pseudo'
>     outdir='./'
>     prefix='Graphane'
>     forc_conv_thr=1.0D-4
>     nstep=10000
> /
>  &system
>     ibrav=  0
>     nat=  32,  ntyp= 3
>     nspin =2
>     starting_magnetization(2) = 0.7
>     ecutwfc =60.0
>     occupations='smearing'
>     degauss=0.002
>     smearing='mv',
> /
>  &electrons
>     conv_thr=1.0D-9
>     mixing_mode='plain'
>     mixing_beta=0.1D0
>  /
> &ions
>    ion_dynamics = 'bfgs'
>   /
> ! &cell
> !    cell_dynamics = 'damp-w'
> !   cell_factor = 10.1D0
> /
> CELL_PARAMETERS {angstrom}
>      4.9363447999999996    0.0000000000000000    0.0000000000000000
>      2.4681723999999998    4.2750000000000004    0.0000000000000000
>      0.0000000000000000    0.0000000000000000   25.0000000000000000
> ATOMIC_SPECIES
> C  12.0111 C.pw-mt_fhi.UPF
> Ni 58.6934 Ni.pw-mt_fhi.UPF
> F  18.9984  F.pw-mt_fhi.UPF
> ATOMIC_POSITIONS {angstrom}
> C        3.116840000      3.174350000      1.386070000
> C        5.584900000      3.174230000      1.386000000
> C        1.882610000      1.036880000      1.385940000
> C        4.350760000      1.036680000      1.385960000
> C        1.882750000      2.461910000      1.888240000
> C        0.648640000      0.324320000      1.888230000
> C        4.350960000      2.461770000      1.888140000
> C        3.116790000      0.324280000      1.888150000
> C        1.882980000      2.461940000      3.476540000
> C        0.648890000      0.324350000      3.476400000
> C        4.351250000      2.461930000      3.476230000
> C        3.117130000      0.324400000      3.476380000
> C        6.819130000      3.887150000      3.951040000
> C        4.351050000      3.887040000      3.950790000
> C        3.116960000      1.749700000      3.950740000
> C        5.585010000      1.749700000      3.950910000
> Ni       6.828000000      3.886970000      5.917170000
> Ni       3.131720000      0.323340000      7.993850000
> Ni       4.367640000      1.035220000     10.009150000
> Ni       4.359850000      3.886850000      5.916790000
> Ni       0.663590000      0.323340000      7.993930000
> Ni       1.899450000      1.035270000     10.009360000
> Ni       5.593900000      1.749490000      5.916940000
> Ni       4.365770000      2.460850000      7.993890000
> Ni       5.601750000      3.172800000     10.009260000
> Ni       3.125750000      1.749380000      5.916700000
> Ni       1.897660000      2.460880000      7.993900000
> Ni       3.133520000      3.172820000     10.009440000
> F        5.584240000      3.175000000      0.000730000
> F        4.350170000      1.037440000      0.000850000
> F        1.882110000      1.037660000      0.000890000
> F        3.116200000      3.175230000      0.000920000
> K_POINTS {automatic}
>   5 5 1 0 0 0
> 
> 
> --
> 
> Best Wishes
> 
> Masood Yousaf
> 
> Ulsan National Institute of Science and Technology, Korea
> 
> 
> 
>